2 files changed, 4 insertions, 7 deletions
diff --git a/src/generic/problemresolver/incremental_expression.cc b/src/generic/problemresolver/incremental_expression.cc
index 1a3d16a4..d579b713 100644
--- a/src/generic/problemresolver/incremental_expression.cc
+++ b/src/generic/problemresolver/incremental_expression.cc
@@ -115,10 +115,10 @@ void not_e::child_modified(const cwidget::util::ref_ptr<expression<bool> > &chil
 
 bool not_e::get_value()
 {
-  return !child->get_value();
+  return !get_child()->get_value();
 }
 
 void not_e::dump(std::ostream &out)
 {
-  out << "~" << child;
+  out << "~" << get_child();
 }
diff --git a/src/generic/problemresolver/incremental_expression.h b/src/generic/problemresolver/incremental_expression.h
index 3284163f..4b6b73c1 100644
--- a/src/generic/problemresolver/incremental_expression.h
+++ b/src/generic/problemresolver/incremental_expression.h
@@ -542,14 +542,11 @@ public:
   void dump(std::ostream &out);
 };
 
-class not_e : public expression_container<bool>
+class not_e : public expression_box<bool>
 {
-  cwidget::util::ref_ptr<expression<bool> > child;
-
   not_e(const cwidget::util::ref_ptr<expression<bool> > &_child)
-    : child(_child)
+    : expression_box<bool>(_child)
   {
-    child->add_parent(this);
   }
 
 public: